VIENNA, W. Va.  It will take up to five years before residents in Ohio and West Virginia who sued DuPont over a chemical used to produce Teflon will know if they have been harmed by the substance, members of a science panel said on Tuesday.

Some results could be released as early as next year, and the scientists on the court-appointed panel say they'll consider steps to keep the public informed of their progress.

The panel plans to do at least nine studies on the chemical, ranging from possible links to heart disease and cancer to its effects on newborns, panel members said at a news conference.

The panelists want to do another study on the effects of ammonium perfluorooctaonate on workers at DuPont's Washington Works plant near Parkersburg along the Ohio River.

The company is fighting the science panel's request for that study, saying it's outside the scope of a 2005 class-action settlement with West Virginia and Ohio residents who claimed their water supplies were contaminated by the chemical.

DuPont has conducted it own studies of its workers, and claims that current and former Washington Works employees had death rates no higher than workers at seven DuPont plants in other states, the population of West Virginia or the rest of the nation. But additional tests would be needed because the study found slightly elevated cases of kidney disease, diabetes and heart disease, DuPont said.

At the time the study was released, Dr. Sol Sax, DuPont's chief medical officer, said the data could not conclusively prove there was no link between the chemical and the case.

For example, while there were 20 diabetes deaths reported by the study, those could be from factors unrelated to the chemical. West Virginia has one of the highest rates of adult diabetes in the country.

The science panel's studies will be completed in stages between 2007 and 2011. The earliest studies will look at possible links between the chemical and heart disease, stroke, diabetes and other disorders. Panelists will review data gathered from health screenings of about 70,000 Ohio Valley residents, including some in southeast Ohio, for those findings.

Based on the findings, DuPont could be required to spend another $235 million to monitor the residents' health.

"This is the biggest study of its kind to look at almost any environmental contagion," said Tony Fletcher, a panelist and epidemiologist at the London School of Hygiene and Tropical Medicine. "I know people are anxious to get answers as quickly as possible."

Under terms of the settlement, the panel has to make quarterly reports on its progress to DuPont, the plaintiffs and the court. On Tuesday, panelists said they'd be open to making those reports public.

"We prefer a more transparent process," Fletcher said.

The panel's work could cost between $10 million and $15 million, said panel member Kyle Steenland, an Emory University epidemiologist. DuPont is paying for the studies as part of the settlement.

Though used since World War II, the chemical's long-term effects on humans are unknown. DuPont has long maintained there are no harmful health effects. The Science Advisory Board for the U.S. Environmental Protection Agency has determined the chemical to be a likely cancer-causing agent in humans.

DuPont officials have said they will continue to use it in its manufacturing processes at the plant. The chemical is distilled out before the final product is completed and so is not present in Teflon or other final products.